Detector arm systems and assemblies

ABSTRACT

A detector arm assembly is provided that includes a stator, a detector head, a radial motion motor, and a detector head belt. The stator is configured to be fixedly coupled to a gantry having a bore. The detector head includes a carrier section that is slidably coupled to the stator and configured to be movable in a radial direction in the bore relative to the stator. The radial motion motor is operably coupled to at least one of the detector head or the stator. The detector head belt is operably coupled to the radial motion motor and the carrier section. Rotation of the radial motion motor causes movement of the detector head in the radial direction.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation in part of and claims priorityto U.S. patent application Ser. No. 14/612,398 filed Mar. 3, 2015,titled “IMAGING SYSTEM USING INDEPENDENTLY CONTROLLABLE DETECTORS”, thedisclosure of which is incorporated herein, which is in turn acontinuation of and claims priority to U.S. patent application Ser. No.14/135,751 filed Dec. 20, 2013, titled “IMAGING SYSTEM USINGINDEPENDENTLY CONTROLLABLE DETECTORS”, the disclosure of which isincorporated herein. The present application is also a continuation inpart of and claims priority to U.S. patent application Ser. No.14/327,178 filed Jul. 9, 2014, titled “WEIGHT COMPENSATION OF RADIATIONDETECTORS,” the disclosure of which is incorporated herein.

BACKGROUND

The subject matter disclosed herein relates generally to medical imagingsystems, and more particularly to Nuclear Medicine (NM) imaging systemswhich can be Single Photon Emission Computed Tomography (SPECT) imagingsystems.

In NM imaging, such as SPECT imaging, radiopharmaceuticals areadministered internally to a patient. Detectors (e.g., gamma cameras),typically installed on a gantry, capture the radiation emitted by theradiopharmaceuticals and this information is used to form images. The NMimages primarily show physiological function of, for example, thepatient or a portion of the patient being imaged.

Conventional SPECT imaging systems include one, two or three gammacameras mounted to a single gantry. These systems are generally notphysically reconfigurable. The gamma cameras (also referred to as heads)are formed from particular materials. In the selection of material,tradeoffs must be made, such as imaging sensitivity, size, cost, etc.Additionally, specific collimation may be provided, which typicallylimits the application of the scanner to a particular type of scan, suchas whole body bone exams, cardiac exams, etc. Thus, conventional SPECTimaging systems have limitations in design and/or operationalcharacteristics. Moreover, there is limited flexibility in these imagingsystems. There is a need for flexibility of an imaging system to becustomizable based on specific patient need and operator costconstraints. There is also a need for imaging systems to automaticallyadjust imaging operations in systems that have changes inconfigurations.

BRIEF DESCRIPTION

In accordance with an embodiment, a detector arm assembly is providedthat includes a stator, a detector head, a radial motion motor, and adetector head belt. The stator is configured to be fixedly coupled to agantry having a bore. The detector head includes a carrier section thatis slidably coupled to the stator and configured to be movable in aradial direction in the bore relative to the stator. The radial motionmotor is operably coupled to at least one of the detector head or thestator. The detector head belt is operably coupled to the radial motionmotor and the carrier section. Rotation of the radial motion motorcauses movement of the detector head in the radial direction.

In accordance with an embodiment, a detector arm assembly is providedthat includes a stator, a detector head, a slider block, and a detectorhead belt. The stator is configured to be fixedly coupled to a gantryhaving a bore. The detector head includes a carrier section that isslidably coupled to the stator and configured to be movable in a radialdirection in the bore relative to the stator. The slider block isinterposed between the detector head and the stator. The slider block isslidably coupled to the stator and configured to be moveable in theradial direction with respect to the stator. The carrier section of thedetector head is slidably coupled to the slider block and configured tobe moveable in the radial direction with respect to the slider block.The detector head belt is operably coupled to the carrier section.Movement of the detector head belt causes movement of the detector headin the radial direction.

In accordance with an embodiment, an imaging system is provided thatincludes a gantry and plural detector arm assemblies. The gantry definesa bore. The plural detector arm assemblies are distributed about thebore. At least some of the detector arm assemblies include a stator, adetector head, a radial motion motor, a detector head belt, and a sliderblock. The stator is configured to be fixedly coupled to the gantryhaving a bore. The detector head includes a carrier section that isslidably coupled to the stator and configured to be movable in a radialdirection in the bore relative to the stator. The radial motion motor isoperably coupled to at least one of the detector head or the stator. Thedetector head belt is operably coupled to the radial motion motor andthe carrier section. Rotation of the radial motion motor causes movementof the detector head in the radial direction. The slider block isinterposed between the detector head and the stator. The slider block isslidably coupled to the stator and is configured to be moveable in theradial direction with respect to the stator. The carrier section of thedetector head is slidably coupled to the slider block and configured tobe moveable in the radial direction with respect to the slider block.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary medical imaging system.

FIG. 2 is a simplified schematic block diagram illustrating a medicalimaging system.

FIG. 3 is a detailed view of a detector column design.

FIG. 4A is a diagram illustrating a radial construction and approach toimage detection.

FIG. 4B is a diagram of the detector columns controlled to move atdifferent points of their radial axis to best scan the specific shape ofa subject.

FIG. 5 is a patient centric view of an exemplary medical imaging system.

FIG. 6 is a perspective view of a gantry design with detector columnsplaced in a partially populated configuration.

FIG. 7A is a perspective view of a gantry design with detector columnsaligned for a supine positioned subject.

FIG. 7B is a perspective view of a gantry design with detector columnsaligned for a prone positioned subject.

FIG. 8 is a flowchart of a method for controlling detector columns.

FIG. 9 is a radial construction view of a gantry design with detectorcolumns aligned for a cardiac application.

FIG. 10 is a radial construction view of a gantry design with detectorcolumns aligned for a brain or pediatric application.

FIG. 11 is radial construction view of a gantry design with detectorcolumns aligned differentially for a brain or pediatric application.

FIG. 12 is radial construction view of a gantry design with partiallypopulated detector columns for a brain or pediatric application.

FIG. 13 is a flowchart of a method for controlling detector columns in apartially populated configuration.

FIG. 14 is a radial construction view of a gantry design withstep-enabled detector columns.

FIG. 15 is a radial construction view of a gantry design with partiallypopulated step-enabled detector columns.

FIG. 16A is a detector column view with fully populated detectorelements.

FIG. 16B is a detector column view with partially populated detectorelements.

FIG. 16C is a detector column view with partially populated detectorelements.

FIG. 17A is a detector column view with only even detector elementspopulated.

FIG. 17B is a detector column view with only odd detector elementspopulated.

FIG. 18 is a detector element view where the outside detector elementsare movable or slide-type.

FIG. 19 is a flowchart of a method for controlling detector columnswhere detector elements are partially populated.

FIG. 20A is a radial construction view of a starting-position gantrysystem where detector elements are partially populated.

FIG. 20B is a radial construction view of moving detector columns in agantry system where detector elements are partially populated.

FIG. 20C is a radial construction view of moving detector columns in agantry system where detector elements are partially populated.

FIG. 21A is a perspective schematic view of a detector arm assembly inan extended position in accordance with various embodiments.

FIG. 21B is a perspective schematic view of the detector arm assembly ofFIG. 21A in a retracted position.

FIG. 22 is a side perspective view of the detector arm assembly of FIG.21A.

FIG. 23 is an opposite side perspective view of the detector armassembly of FIG. 21A taken from an opposite side as FIG. 22.

FIG. 24A is a perspective view of a cover system in an extended positionin accordance with various embodiments.

FIG. 24B is a perspective view of the cover system of FIG. 24A in aretracted position.

FIG. 25 is a perspective view of an imaging system in accordance withvarious embodiments.

FIG. 26A provides a schematic view of a detector arm assembly in aretracted position in accordance with various embodiments.

FIG. 26B provides a schematic view of the detector arm assembly of FIG.26A in an extended position.

FIG. 27A provides a schematic view of a detector arm assembly in aretracted position in accordance with various embodiments.

FIG. 27B provides a schematic view of the detector arm assembly of FIG.27A in an extended position.

FIG. 28A provides a schematic view of a detector arm assembly in aretracted position in accordance with various embodiments.

FIG. 28B provides a schematic view of the detector arm assembly of FIG.28A in an extended position.

FIG. 29A provides a schematic view of a detector arm assembly in aretracted position in accordance with various embodiments.

FIG. 29B provides a schematic view of the detector arm assembly of FIG.29A in an extended position.

FIG. 30 provides a schematic depiction of various gantry locations inaccordance with various embodiments.

DETAILED DESCRIPTION

The foregoing summary, as well as the following detailed description ofcertain embodiments and claims, will be better understood when read inconjunction with the appended drawings. To the extent that the figuresillustrate diagrams of the functional blocks of various embodiments, thefunctional blocks are not necessarily indicative of the division betweenhardware circuitry. Thus, for example, one or more of the functionalblocks (e.g., processors, controllers or memories) may be implemented ina single piece of hardware (e.g., a general purpose signal processor orrandom access memory, hard disk, or the like) or multiple pieces ofhardware. Similarly, the programs may be stand alone programs, may beincorporated as subroutines in an operating system, may be functions inan installed software package, and the like. It should be understoodthat the various embodiments are not limited to the arrangements andinstrumentality shown in the drawings.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” are not intended to beinterpreted as excluding the existence of additional embodiments thatalso incorporate the recited features. Moreover, unless explicitlystated to the contrary, embodiments “comprising” or “having” an elementor a plurality of elements having a particular property may includeadditional such elements not having that property.

Various embodiments provide a medical imaging system, and in particular,a Nuclear Medicine (NM) imaging system having a gantry with a pluralityof different types of imaging detectors mounted thereto. For example, invarious embodiments of an NM imaging system, a Single Photon EmissionComputed Tomography (SPECT) imaging scanner is provided that includes aplurality of detectors with a combination of different types ofdetectors that acquire SPECT image information. The various embodimentsmay include detectors formed from different materials, having differentconfigurations or arrangements, having different collimation, etc. Thesystem may be configured to perform single isotope or multi-isotopeimaging.

It should be noted that although the various embodiments are describedin connection with a particular NM imaging system, such as a SPECTdetector system, the various embodiments may be implemented inconnection with other imaging systems, such as a Positron EmissionTomography (PET) imaging system. Additionally, the imaging system may beused to image different objects, including objects other than people.

A medical imaging system 10 may be provided as illustrated in FIG. 1. Asubject 18 can be a human patient in one embodiment. It should be notedthat the subject 18 does not have to be human. It can be some otherliving creature or inanimate object in various embodiments. The subject18 can be placed on a pallet 14 that can move a subject horizontally forlocating the subject in the most advantageous imaging position. The bedmechanism 16 can raise and lower the pallet 14 vertically for locatingthe subject in the most advantageous imaging position. The gantry 12 isshown as circular in one embodiment. In other embodiments the gantry 12may be of any shape such as square, oval, “C” shape, or hexagonal.

FIG. 2 shows the medical imaging system 20 in accordance with anotherembodiment. The medical imaging system 20 may be provided having aplurality of NM cameras configured as SPECT detector columns 22 a-22 f.It should be noted that the various embodiments are not limited to themedical imaging system 20 having six detector columns 22 as shown or tothe sizes or shapes of the illustrated detector columns 22. For example,the medical imaging system 20 may include more or less detector columns22 having different shapes and/or sizes, or formed from differentmaterials. The medical imaging system 20 in various embodiments isconfigured as a hybrid SPECT system having a plurality of detectorcolumns 22, wherein at least two of the detectors are formed fromdifferent materials, have different configurations or arrangements, havedifferent collimation, or are otherwise different. Detector columns canbe called detector units in some embodiments.

In operation, a subject, such as a patient 24, is positioned inproximity to the one or more of the detector columns 22 for imaging. Theimaging system 20 can then re-adjust the detector columns 22 furtherfrom or closer to the patient 24 or patient area of interest as needed,which is heart 28 in an example embodiment. Imaging of the patient 24 isperformed by one or more of the detector columns 22. The imaging by eachof the detector columns 22 may be performed simultaneously,concurrently, or sequentially.

The position of the detector columns 22 may be varied, including therelative position between detector columns 22, tilt, angle, swivel, etc.of the detector columns 22. Additionally, each of the detector columns22 may have a corresponding collimator 26 a-26 f mounted or coupledthereto. The collimators 26 a-26 f likewise may be of different types.One or more detector columns 22 may be coupled to a different type ofcollimator 26 (e.g., parallel hole, pin-hole, fan-beam, cone-beam,etc.). Accordingly, in various embodiments, the detector column 22wholly includes collimator 26.

The detector columns 22 may include single crystal, or multi-crystal,detectors or pixelated detectors or scintillator based detectors thatare configured to acquire SPECT image data. For example, the detectorcolumns 22 may have detector elements formed from different materials,such as semiconductor materials, including Cadmium Zinc Telluride(CdZnTe), often referred to as CZT, Cadmium Telluride (CdTe), andSilicon (Si), among others, or non-semiconductor scintillator materialssuch as different types of crystal scintillators, for example, SodiumIodide (Nap, Bismuth Germanate (BGO), Cerium-doped Lutetium YttriumOrthosilicate (LYSO), Gadolinium Oxyorthosilicate (GSO), Cesium Iodide(CsI), Lanthanum(III) bromide (LaBr₃), among others. Additionallysuitable components may be provided. For example, the detector columns22 may be coupled to photosensors, such as an array of Photo-MultiplierTubes (PMTs), an Avalanche Photodiode Detector (AFD), etc.

The imaging system 20 can also include a detector controller 30 thatoperates to control the movement of the detector columns 22 and/or thecollimators 26. For example, the detector controller 30 may controlmovement of the detector columns 22, such as to rotate or orbit thedetector columns 22 around a patient 24, and which may also includemoving the detectors closer or farther from the patient 24 andpivoting/swiveling the detector columns 22, such that more localizedmovements or motions are provided. The detector controller 30additionally may control the orbital rotation of the detector columns 22around the edges of the gantry bore, such that the detector columns 22are at a new angle to the patient 24 than previously. The detectorcontroller 30 may also optionally control movement of the collimators26, such as independently of the detector columns 22. It should be notedthat one or more the detector columns 22 and/or the collimators 26 maymove during imaging operation, move prior to, but remain stationaryduring imaging operation, or may remain in a fixed positioned ororientation. In various embodiments, the detector controller 30 may be asingle unit controlling movement of both the detector columns 22 and thecollimators 26, may be separate units, or may be a single unitcontrolling only operation of the detector columns 22 or may be a singleunit controlling only operation of the collimators 26.

The imaging system 20 also includes an image reconstruction module 34configured to generate images from acquired image information 36received from the detector columns 22. For example, the imagereconstruction module 34 may operate using NM image reconstructiontechniques to generate SPECT images of the patient 24, which may includean object of interest, such as the heart 28 of the patient. The imagereconstruction techniques may be determined based on the installationstatus of detector column 22 acquiring the image information 36 andsending to image reconstruction module 34 and/or processor 32.

Variations and modifications to the various embodiments arecontemplated. For example, in a multi-headed system, namely a systemhaving two or more detector columns 22, each detector column 22 may beformed from different materials and have different collimators 26.Accordingly, in at least one embodiment, one detector combination may beconfigured to obtain information for an entire field of view (FOV), suchas the entire spine, while another detector combination is configured tofocus on a smaller region of interest (ROI) to provide higher qualityinformation (e.g., more accurate photon counting). Additionally,information acquired by one detector combination may be used to adjustthe position, orientation, etc. of at least one other detectorcombination during imaging.

The image reconstruction module 34 may be implemented in connection withor on a detector controller 30 and/or processor 32 that is coupled tothe imaging system 20. Optionally, the image reconstruction module 34may be implemented as a module or device that is coupled to or installedin the detector controller 30 and/or processor 32. Each processingmodule may be a separate hardware module or software module, or combinedtogether into one chip or module in various embodiments.

The image information 36 received by the processor 32 and/or imagereconstruction module 34 may be stored for a short term (e.g., duringprocessing) or for a long term (e.g., for later offline retrieval) in amemory 38. The memory 38 may be any type of data storage device, whichmay also store databases of information. The memory 38 may be separatefrom or form part of the processor 32. A user input 39, which mayinclude a user interface selection device, such as a computer mouse,trackball and/or keyboard is also provided to receive a user input. Theuser input may direct the processor 32 to send a detector control signalto the detector controller 30 for alteration of the detector column 22arrangement in the gantry bore. Optionally, the user input 39 may beconsidered by the processor 32 as a suggestion and the processor 32 maychoose to not execute the suggestion based on criteria.

Thus, during operation, the output from the detector columns 22, whichmay include the image information 36, such as projection data from aplurality of detector/gantry angles is transmitted to the processor 32and the image reconstruction module 34 for reconstruction and formationof one or more images. The reconstructed images and other user outputcan be transmitted to a display 40 such as a computer monitor or printeroutput. The reconstructed images and other user output can also betransmitted to a remote computing device via network 42.

Different combinations and variations of detector columns 22 and/orcollimators 26 will now be described. It should be noted that thevarious embodiments are not limited to a particular detector,collimator, or detector combination, but may include any imaging systemhaving a plurality of different types of detector columns 22 and/orcollimators 26, for example, having at least two detector columns 22 ofa different type or design. Additionally, the number of detector columns22 and the arrangement thereof may be varied as desired or needed, forexample, based on the type of imaging to be performed or the type ofimage information to be acquired. Accordingly, various embodimentsinclude the imaging system 20 having a plurality of detector columns 22,wherein at least two of the detector columns 22 are different and areconfigured to perform imaging of the patient 24 (or other object).

For example, in one embodiment, illustrated in FIG. 2, a configurationis provided having one detector column 22 a formed from one material andthe remaining detector columns 22 b-221 formed from a differentmaterial. In the illustrated embodiment, the detector column 22 a isformed from a NaI material and the remaining detector columns 22 b-221are formed from a CZT material. Accordingly, in this configuration, asingle NaI detector column 22 a and a plurality of CZT detector columns22 b-221 are provided. The detector columns 22 a-221 may be sized andshaped the same or differently. For example, in the embodimentillustrated in FIG. 2, the NaI detector column 22 a is larger than eachof the CZT detector columns 22 b-221, such that the NaI detector column22 a can image the entire patient 24 and the CZT detector columns 22b-221 are configured to focus on a portion of the patient 24, such asthe heart 28. In this embodiment, one or more of the CZT detectorcolumns 22 b-221 may be positioned and oriented at different angles ortilted differently to provide focused imaging. However, one or more ofthe CZT detector columns 22 b-221 may be angled or tilted the same. Inthe embodiment of FIG. 2, the CZT detector columns 22 b-221 are angledsuch that together the CZT detector columns 22 b-221 focus on theoverall body of the patient 24, instead of on a particular ROI, such asthe heart 28. Thus, one or more detector columns 22 may be arranged andconfigured to cover an entire FOV of an imaged, while one or more otherdetectors are arranged and configured to cover a focused FOV within theobject.

It should be noted that as used herein, a set of detectors is generallyreferred to as the detector columns 22 and a set of collimators isgenerally referred to as the collimators 26. Moreover, the use of letterdesignations after the numeral designation for the detector columns 22and collimators 26 are used for ease of illustration and do notnecessarily represent the same detector columns 22 or collimators 26 inthe various embodiments or figures. Thus, the letter designationrepresents the relative positioning of the detector columns 22 orcollimators 26 and not necessarily the type or kind of detector.Additionally, the size and shape of the detector columns 22 may bevaried as desired or needed.

In FIG. 2, the collimators 26 a-261 may be the same or may be different.For example, the collimator 26 a may be of a first type, such as aparallel hole collimator, while the collimators 26 b-261 may havedifferent types (e.g., converging, diverging or pinhole) based on adesired or required sensitivity or resolution, as well as the positionand orientation of the detector column 22 on which the collimator 26 iscoupled. Thus, the collimators 26 may be of any type.

FIG. 3 shows a more detailed implementation of detector column 22 inaccordance with an embodiment. Column arm 44 attaches to a gantry andprovides support for and includes a radial motion rail 46, radial motionmotor 48, and detector head 50. The radial motion motor 48 controls themovement of the detector head 50 by extending or retracting the detectorhead 50 along the radial motion rail 46. This provides customizabilityand flexibility to the imaging system. The detector column can includetelescopic covers that allow it to extend and contract as it movesradially in and out.

The detector head 50 includes a sweep motor 52, detector elements 54,and collimator 56. The detector elements 54 can be CZT modules or otherdetector element modules discussed throughout for detecting imagingdata. Sweep motor 52 controls the rotation angle of the detector head 50in relation to the arm 44. The sweep pivoting axis 53 shows the rotationangle axis of the detector head 50. The detector controller 30 canprovide instruction and control to either or both of the radial motionmotor 48 and sweep motor 52. Thus, each detector column 22 isindependently controllable in the radial location as well as the angleof tilt of the detector head 50. The radial motion motor 48 and sweepmotor 52 can be two separate motors as shown in the embodiment of FIG.3. Alternatively, the functionality of the two motors may be provided byone motor.

FIG. 4A shows a radial construction of an imaging system where twelvedetector columns 22 are placed at a consistent angle, thirty degrees inthis example, from each other along the inside of a gantry bore. Thus,the detector columns 22 are uniformly distributed in this example. Eachdetector column 22 is movable along a radial axis. This allows thedetector columns 22 to be closer or further from a subject 18 forimaging. The circles in the figure depict the location of the detectorhead 50 of detector column 22. The detector columns are shown along thedotted line as their outer limit position in this view of oneembodiment. The dual head radial arrows depict the in-out direction ofmotion of the detector columns 22.

FIG. 4B shows a radial construction where twelve detector columns 22have their heads placed at a consistent angle and have been movedradially inward to be in positions close to a patient 24. As FIG. 4Bshows, some of the detector heads are further towards the center oftheir radial axis than others. This allows for high-quality imagingresults with varied-sized objects.

FIG. 5 shows a NM medical imaging system 60 scanning the mid-section ofa patient 24 where the detector columns 22 including detector heads 50are only partially populated, according to one embodiment. Compared to afully populated system, such as FIG. 4A and FIG. 4B, a partiallypopulated system includes the installation of a partial amount ofdetector columns 22 that an imaging system is configured to support.FIG. 5 also demonstrates the planes of scanning including the sagittalplane, coronal plane, and transverse plane. Based on the specific ROI ortype of image scan selected, imaging of a patient may only need to befocused in areas of these planes. Some embodiments herein are directedtowards tailoring partially populated imaging systems, such as NMimaging system 60 for maximal image quality and lowest scan time giventhe situation and installation information constraints.

FIG. 6 shows a gantry 62 that can support twelve detector columns 22.The gantry 62 can contain all of the features of the FIG. 2 system inone embodiment. Only six detector columns 22 have been installed ingantry 62. This could be for lower cost of the system, easiermaintenance, or other reasons, for example. Thus, the system of FIG. 6is a partially populated NM imaging system. It is partially populatedbecause the installation information for the system indicates that thesystem can support twelve detector columns 22, but only six detectorcolumns 22 are installed. The locations where a detector column can beinstalled or attached can be called receiver locations 64 in someembodiments. The detector columns 22 in FIG. 6 are shown in a radiallyextended position. The detector columns 22 of this embodiment can bedetached by a non-technical operator. They can be detached from one ofthe twelve receiver locations 64 and snapped, screwed, clamped, orotherwise attached, to one of the open receiver locations 64 around thegantry 62. Thus, detector columns 22 are detachable and attachable tocreate further system configurations. This system, in some embodiments,can be considered a modular system. A non-technical operator can be onewho has not had specialized or advanced training on the installation andadjustment of the imaging system. A technical operator could be a fieldengineer, for example.

Installation information can be dynamically updated by processor 32 ordetector controller 30 based on information from installationverification elements in receiver locations 64, and stored in memory 38in one embodiment. Installation verification elements can be any sort ofswitch, button, sensor, or other device that detects the presence ofhardware installed or not installed in the system. Installationverification elements of receiver locations 64 are one way that thesystem can detect and update installation information. Installationinformation in one embodiment relates to the detector column arm 44being physically attached to gantry 62. Further, installationinformation in another embodiment detects both physical attachment plusa fully functioning arm. In this embodiment, if any of the radial motionmotor 48, sweep motor 52, and/or detector elements 54 are inoperable,even though the detector column 22 is attached to the gantry 62, theinstallation information could indicate the detector column asuninstalled and/or inoperable. Installation information can alsoindicate the population of specific detector elements 54, as furtherdiscussed below.

Installation information is also called configuration information insome embodiments. This is because installation information givesinformation related to the current hardware configuration in the imagingsystem, and can be dynamically updated. Thus, installation information,sometimes called configuration information, is not just the initialsetup information of the system when delivered to a customer, but isinformation dynamically updated based on many hardware factorsthroughout the lifetime of the system.

FIG. 7A shows a gantry 62 that can support the installation andoperation of twelve detector columns 22. Only seven detector columns 22have been installed in gantry 62. This is an example of a partiallypopulated imaging system. The detector columns 22 in FIG. 7A are shownin a radially extended manner, but not as radially extended as shown inFIG. 6. This configuration may be best for a supine patient where theheart, as an example of a ROI, is near the top and side of the gantry.The detector controller 30 can identify from the installationinformation that there are seven installed detector columns 22 and inwhich receiver locations 64 they reside around the bore of gantry 62.Then the detector controller 30 rotates the detector columns 22 aroundthe bore to the ideal position for the particular region of interestedbased on user input 39 or information of the test and patient from othersources, such as memory 38 or network 42. This ideal position can alsobe called the position location essential for imaging information. Thus,moving the detector columns 22 and detector heads 50 into the bestposition for capturing essential imaging information for each type ofprocedure is important and is done by the embodiments.

FIG. 7B shows a gantry 62 where the seven detector columns 22 have beenrotated by machinery in an orbital manner inside the gantry 62 that iscontrolled by the detector controller 30 to move the detector columns 22into positions with new radial axes to a patient. The detector columnscan be rotated rotate three-hundred sixty degrees around a subject to beimaged, which is patient 24 in this example. As can be seen fromcomparing FIG. 7A to FIG. 7B, detector column 22 a has been rotated froman axial position below a patient 24 to an axial position above thepatient 24. Detector column 22 g, consequently, has moved from above tobelow the patient in this example. The example in FIG. 7B may be bestfor prone patients where the heart, as an example of a ROI, is near thebottom and side of the gantry.

FIG. 8 is a flowchart depicting a method of operation with respect toone embodiment. The steps as shown do not necessarily have to flow inthe order as listed, but are shown in this order just as an example.

In step 80, the system determines installation information. This helpsdetermine what operations and features are available in the system.Installation information, in some embodiments, can included detectorcolumn attachment status 71 which indicates in which receiver locations64 detector columns 22 are installed and in which receiver locations 64detector columns 22 are not installed. This can tell the system both howfar each detector unit can be extended radially as well as how muchorbital movement of the detector units will need to occur duringoperation. Installation information can further include sweep motorstatus 72. This status can indicate whether each detector column 22 hasa sweep motor 52 for head rotation capability, whether the sweep motor52 is operable, and its range of motion (in circumstances when somedetector heads 50 are configured to rotate further than others), or notresponding. Installation information can further include radial motionmotor status 73. This status can indicate whether each detector column22 has a radial motion motor 48, its radial motion distance, radiallocation status, and whether or not the motor is currently operable.Installation information can further include detector elementconfiguration status 74. This status can indicate the specific locationswhere detector elements 54 are installed and specific locations wheredetector elements 54 could be installed but are not installed. See FIGS.16-17 for example. This status can also indicate what materials arebeing used to detect the imaging data. Each detector column or detectorelement could have different scintillator or semi-conductor materialsinstalled. This detector element configuration status 74 can alsoindicate what collimator 56 structure is used in the detector head. Asmentioned above, different collimators 56 can be utilized in differentdetector heads 50. Installation information can further include otherinstallation factors 75, including gantry rotation ability. This is anindication of how many degrees of rotation (or how many ‘steps’) thegantry can rotate detector columns around the orbit of the gantry.Installation information can further include other installation factors75 such as the room the imaging system is set up in, factors input by auser, safety information, and other types of information about theinstallation of the system overall, not just the installation status ofthe components in the imaging system. For example, many SPECT systemsare placed in SPECT/CT (computed tomography) combined system, and thesystem may also acquire information related to what CT setup isinstalled.

In step 82, the system compares the installation information with what aspecific imaging scan will be and subject information. The imaging scantype information 76 (such as CT, SPECT, PET, MRI, or can be related tothe specific radiopharmaceutical being used or the type of medicalexamination performed) can be considered. The region of interestinformation 77 (such as cardiac, brain, thyroid) can be considered. Thepatient position information 78 on the pallet or bed can be considered.The subject size, age, gender, weight, and other medical characteristics(patient body-type information or patient medical information or subjectspecific information) can impact the process relating to other userinput factors 79. The imaging scan is generally a NM imaging scan basedon acquiring SPECT data, but the system could be used in other scanningarrangements for other types of imaging information.

In step 84, the imaging system 20 develops an optimal scanning scenariobased on the installation information compared with the subject scaninformation. For example, if the scan is a cardiac scan and the subjectpatient is small, a selected scenario would set the radial extension ofthe arms to high and the arms will be recommended to move orbitallytowards the sides of the gantry closest to the heart. If the angle ofthe subject is difficult, the scenario may include rotating some of thedetector heads 50 to be more accurately aligned towards the subject.

In step 86, the system makes a decision whether the scanning scenariocan be performed within a threshold time. This can also be called atotal imaging operation time prediction. This determination considershow long it will take the system to do the full requested imaging basedon the imaging time plus system rearrangement time when it is beingreconfigured to get additional scanning data. The threshold can be basedon an ‘acceptable’ time set by a user, a subject patient preferred time,a normalized time compared to most scans of the type being done, and/orrelated to a threshold of safety. The total imaging operation timeprediction also considers how long it may take to adjust the patient andhow long it takes to adjust the detector columns, detector heads, and/ordetector elements. If the time to complete the optimal scanning scenariois higher than a threshold, the system goes to step 88, otherwisecontinuing on to step 86.

In step 88, a user is notified that the current installation setup ofthe system may not be able to complete the requested scan in a thresholdtime. A list of options may also be presented to the user relating tosteps the user can take to mitigate any issues or override the issue.

In step 90, the user decides whether to alter the installationarrangement/setting of the system or not. The user can input a responseback to the system of their intention. The user can adjust the systemmanually, in some respects, and automatically through computer controlin other respect. If a user adjusts the system, thus alteringinstallation information, the method returns to step 80 to re-evaluatethe installation information. If the user is OK with the time thresholdbeing met or exceeded, the system can proceed to step 92.

In step 92, the system performs the physical modifications recommendedin the optimal scanning scenario. This can include configuring thedetector column axial position around the gantry orbit, the axial radiuslocation for scanning (how far or close to patient along the axialradius), detector head angle as controlled by the sweep motor, and otherphysical adjustments discussed throughout.

In step 94, the subject is in the system and the images are acquired. Ifmultiple physical positions of the detector columns 22, detector heads50, and/or detector elements 54 are needed, the system adjusts themduring the imaging operation at step 96. This is an example ofdynamically adjusting of the physical system.

In step 98, the final requested image data is output. A reconstructionalgorithm may be applied after the image data acquisition or proactivelyduring the image data acquisition. The output can be to a display,network connected computing device, a printer, picture archive andcommunication system (PACS) or other output location.

Because the imaging system of at least one embodiment can start withlimited installation equipment, the system can perform lower-costimaging, while also providing upgradability. For example, if a hospitalhas a small budget and only will perform cardiac scans, they canpurchase a system with detector columns setup best for cardiac and notincluding additional detector columns that can add additional cost. Thehospital can still do other types of scans, but will have to wait longerfor the system to re-adjust to different image scan scenarios to handlethe different scan type. This can add time and sometimes provide a lowerquality image than a fully populated or otherwise customized system. Thehospital can upgrade and purchase more detector columns, or detectorcolumns with the optional detector head sweep feature, or detectorcolumns with the optional detector radius extension feature, or detectorcolumns with multiple types of image acquisition materials and installthem into the system for improved performance. This also applies todetector elements. Detector elements are a driver of cost as well. So ahospital, for example, could purchase one with lower detector elementcount (with longer scan time, seen for example in FIG. 16B) and upgradelater.

FIG. 9 shows the front view of an imaging system specifically set totarget a cardiac image. A patient 100 lies on a bed 102, which couldalso be similar to the pallet 14 and bed mechanism 16 of FIG. 1, withtheir heart 104 on the left side of the system in this view. For thiscardiac application, distant locations 106 can either be un-populated(empty) of any detector columns or they can be set to not receive images(such as, to save electricity). In this case, the unused detectorcolumns may be retracted and not advance towards the patient. This canalso be beneficial when one of the detector columns in the system has abroken aspect, such as one of its motors, wires, arm, or detectorelements. They system can orbitally move that broken detector columninto a distant location 106 to not be used in the current scan. Anotification can be sent to the user or operator regarding the issue,the user or operator can be at a local display or remote facility. Thesystem, in this embodiment, does not need to use any detector columns indistant locations 106 because they are too far from the subject, forexample, and the distance reduces resolution of the image and addsattenuation from the gamma ray source, patient heart 104 in thisexample. Thus, the image contribution of any detector columns in distantlocations 106 is negligible.

FIG. 10 shows the front view of an imaging system specifically set totarget a small subject such as a brain, a limb, or pediatric image. Inthis imaging operation, the patient area 108 is smaller than a fullbody. The detector columns 22 have their heads extend radially fromtheir starting position on the outer limits of the gantry towards thepatient 108 to get the best image resolution by being closer, in thisexample. This example shows a case where a fully populated, all twelvedetector column receiver locations in the gantry are filled withdetector columns, system is not necessarily ideal, because the armscollide as they try to get the closest distance from the patient area108.

FIG. 11 shows another front view of an imaging system specifically setto target a brain or pediatric image. This is a similar situation toFIG. 10, but the system, following the flowchart steps of FIG. 8 or FIG.13, determines the installation information (in this case, as anexample, a fully populated system with twelve detector columns where theradial motion motors are all in operation), takes in the subject scaninformation (either the fact that the scan type is a head—small in size,or the subject type is a child—small in size), and develops an optimalscanning scenario. This case includes some fully extended detectorcolumns 110, in this case every other, with some not-fully extendeddetector columns 112. In FIG. 10, an implementation with fully extendeddetector columns 110 was not possible because of detector columncollision. By not uniformly extending the detector columns, such animplementation is possible in the scenario of FIG. 11.

FIG. 12 shows another front view of an imaging system specifically setto target a brain or pediatric image. In this system, similar to FIG. 6,only half of the possible receiver locations for detector columninstallation have detector columns installed. A user, either technicallysavvy or not technically savvy depending on specific hardwareimplementation, could have removed the detector columns that were notneeded from the system. A customer could order from the supplier animaging system with only some of the detector columns installed, forcost reasons for example. Or, a customer could purchase a fullypopulated system of FIG. 10 or FIG. 11, and some of the detachabledetector columns can be removed at a later time. This createsflexibility and upgradability for users and owners of the system. If aparticular imaging system user simply focuses on brain imaging in theirimaging operations, they may never need the extra detector columns, withrelated cost and maintenance, of a fully populated system of FIG. 10 orFIG. 11.

FIG. 13 shows a flowchart of the operation of the system in anembodiment. In step 130, the system operator gives a user input 39indicating the procedure type, such as a brain scan, breast scan,cardiac scan, or other object scan.

In step 132, the system creates an optimal scanning technique of how thedetector columns 22, detector heads 50, and detector elements 54 shouldbe arranged. This optimal scanning technique can be based on organ type,patient size, desired acquisition time, for example. These can be userinput values for each, or system detected values. For example, thepatient size could be automatically determined by a quick scan of theenvironment.

In step 133, the system determines if the hardware installed in thesystem can perform the optimal scanning technique. This can also bethought of as a determination if the optimal hardware setup is in placefor the current situation based on installation information. If thesystem has all of the hardware installed for an optimal result (meaningthe installation information matches the optimal scanning arrangement),the system proceeds to step 135. Otherwise, it proceeds to step 134.

If the system reaches step 134, the system has used the installationinformation to determine that the optimal scanning technique cannot beperformed. This could be, for example, that one detector column ismissing so the optimal arrangement cannot be accomplished and the scantime will necessarily be longer. In step 134, the system, using theinstallation information and/or other factors related to the scan typeor scan object, creates a new adaptive scanning technique to meet thesituation or retrieves a previously saved adaptive scanning techniquefrom memory that can apply to the current situation. The adaptivescanning technique can add time to the scan, but can be lower costbecause the operator or customer does have to pay for a fully populatedor fully featured system. Optionally, the adaptive scanning techniquemay comprise gantry motion or rotation or both in order to bring anoperating detector to a location where a missing or inoperative detectorshould have been.

In step 135, the system performs an imaging operation on the subject.The imaging operation is completed by controlling the hardware elementsof the system in a manner fitting the selected scanning technique(either optimal or adaptive). This controlling can include, but is notlimited to, extending or retracting detector columns 22, rotatingdetector heads 50 to different scan angles, or moving detector columns22 around the gantry orbitally to a new radial angle to the subject(such as the orbital movement of detector columns between FIG. 7A andFIG. 7B).

In step 136, the system adapts a reconstruction algorithm based on animage acquisition scenario and reconstructs the imaging informationpicked up on the detector elements 54 using image reconstruction module34. The image reconstruction process or algorithm can be adapted to bemore compatible with the selected scanning technique. This creates thehighest quality image possible given the hardware constraints of thesystem.

In step 138, the system displays an image output to a user, operator,patient, or other party. This can be on display 40 or at some remotelocation after the image output has been transmitted over network 42.

FIG. 14 shows the ability of the gantry to rotate the detector columnsin an orbital manner. Detector columns 22 are placed at even angles fromeach other in this fully populated example. The gantry rotation range146 is a full three-hundred sixty degree rotation in some embodiments,as low as zero degrees in other embodiments, and may be anywhere inbetween. Again, this is an upgradeable feature and related toinstallation information. The gantry can be initially installed withhardware only supporting thirty degree rotation, for example. Thecustomer could then purchase an upgrade with a few additional motors orhardware components to be installed to give the gantry one-hundredeighty or three-hundred sixty degree rotation ability. FIG. 14 shows asystem with a thirty degree gantry rotation range 146. This allows atwelve detector column system to give coverage every ten degrees. FIG.14 shows detector column 148A at an initial position 140, step 1 ofrotation. Detector columns 148B and 148C are the same physical detectorcolumn as 148A, just in new orbital positions 142 and 144, respectively.FIG. 14 further shows detector column 150A rotated to different orbitalpositions 150B and 150C. Thus, the system can rotate orbitally to moveall detector columns to a new radial angle from a subject, or just movespecific detector columns to new locations without rotating all of thedetector columns in the system. FIG. 14 shows the latter arrangement,when only detector columns 148A and 150A are rotated an all otherdetector columns 22 remain at the same radial angle with respect to asubject.

FIG. 15 shows the ability of a partially populated gantry to rotate thedetector columns, such as detector column 154, in an orbital manner. Inthis example, the column detectors only partially populate the gantrylocations. Six gantry locations, at sixty degree intervals have detectorcolumns installed, while alternating six locations are vacant. Thegantry rotation range 152 is sixty degrees in this example, and adetector column 152 has six ‘steps’ or locations of scanning, each setat a ten degree offset.

FIG. 16A is a detailed view of a fully populated detector head 50. Itshows detector elements 54 that include the detector materials to pickup photons or other imaging indicators in an imaging operation. Thedetector head 50 of FIG. 16A is considered fully populated because allseven of the locations where detector elements can be installed haveinstalled detector elements 54. Whether a detector element 54 isinstalled or vacant can be one type of installation information. Also,the type of materials embedded in each detector element 54 can be onetype of installation information. The head may have any number ofdetector element locations; seven is just the example of this particularembodiment.

FIG. 16B is a detailed view of a partially populated detector head 160.The detector elements 54 are installed in a staggered fashion, withvacant detector element locations 162. This installment configurationprovides for a lower cost detector column 22, because much of the costof a detector column comes from the detector element 54. The collimatormay be sized to the number of populated detector elements. In this case,even locations are vacant, and odd locations are populated.

FIG. 16C is a detailed view of a partially populated detector head 164.The detector elements 54 are all installed towards one side of thedetector head 164. Vacant detector element locations 162 are towards theother side of the detector head 164. This installation configuration canbe good for narrow field of view imaging operations. The narrow field ofview installation configuration can be good for small organ scanning,such as having five detector elements 54 installed for brain scans (20cm coverage), four detector elements 54 installed for heart scans (16 cmcoverage), or two detector elements 54 installed for thyroid scans (8 cmcoverage). As an example, if a system including only two detectorelements 54 per detector column 22 was trying to complete a brain scan,the time to do the brain scan could be much longer or the image resultcould be much worse. Step 86 of FIG. 8 could determine this and notifythe user at step 88. The user could then swap out the current detectorcolumns with others that have five detector elements per detectorcolumn. The system would then dynamically update the installationinformation in step 80. Thus, the system is reconfigurable andcustomizable to fit user needs and imaging situations. A medicalfacility, for example, in which the majority of scans are of limitedaxial extend, such as brain, thyroid, heart, and the like may choose theappropriate population for their system to reduce cost. Axial FOV largerthan the width of the populated section of the heads, for example, wholebody scanning, may be achieved with axial motion of the patient table.

FIG. 17A and FIG. 17B show detailed views of partially populateddetector heads. In a system, such as FIG. 20, where a gantry has fullypopulated detector columns 22, the odd numbered detector columns couldhave odd populated detector elements, such as in detector head 170. Theeven numbered detector columns could have even populated detectorelements, such as detector head 172. Thus, the installation informationcan vary from one detector column to the next detector column.

Optionally, the populated detector elements in the detector columns arearranged in an alternating fashion such that a combination of detectorelements in two adjacent detector columns creates a full set. Thisallows for acquiring a full data set by positioning odd columns in theposition where an even column was before, and combining the dataacquired from the two columns from at the same position. It should benoted that positions may not be identical, but only proximate to enablesuccessful reconstruction. Optionally, adjacent columns may have atleast one common populated element or a common missing element and yetenable successful reconstruction. Generally, “over sampling” as createdby common populated element is easily compensated in the reconstructionand reduces the noise in the parts of the scanned body which was oversampled. Under sampling as created by common unpopulated element mayalso be compensated in the reconstruction, but it may increase the noisein the parts of the scanned body which was under sampled. However, notall parts of the body need to be scanned at the same accuracy, and thusunder sampling may be tolerated if aimed at less critical organs.

FIG. 18 shows a detailed view of a detector head design of anotherembodiment. The detector elements of detector head 180 are arranged in agrid. When targeting a specific organ or subject, the direct detectorelements are most important for image quality, and the detector elementsfurther to the side are only necessary for peripheral information. Thus,to save cost, detector heads can be configured as shown. The middleregion with fixed detector elements 184 give five times bettersensitivity than the detector elements 182. This is because slidingdetector elements 184 move behind the collimator during the imagingoperation to collect data at various points. This movement can becontrolled by a motor such as the sweep motor 52 or additional motorinstalled. The organ or subject, such as a heart, could be centered inthe middle of the detector head in an optimal scanning scenario. Aneffective field of view for such a system could be 36 by 20 centimeters.A quality field of view for such a system could be 20 by 20 centimeters.The installation information for this embodiment can include the number,location, and movement ability of each detector element. The detectorhead 180 is very useful in system installation configurations where thenumber of total detector columns is low, because each detector columnwould be able to handle more detection information. In this embodiment,the collimator could be attached to the detector head itself orindividual detector elements. Thus, the movable detector elements 182could have a collimator attached thereto so that a collimator would nothave to be manufactured for the whole space, saving cost.

FIG. 19 is a flowchart of one embodiment in which different detectorelement configurations are applicable to the installation information.Dotted box 185 indicates that the steps 186-194 are examples of thetypes of determinations that could be made in step 80 of FIG. 8. Step200 is an example of type of determination that could be made in step 82of FIG. 8. And dotted box 198 indicates that the steps 202-208 areexamples of the types of determinations that could be made in step 84 ofFIG. 8.

In step 186, the system collects data from various parts of the overallsystem (such as shown in steps 71-75 of FIG. 8). Based on that data, thesystem determines whether the system has a staggered setup, in step 188,a sliding setup, in step 190, a narrow FOV setup, in step 192, or acustom detector element setup, in step 194. A staggered setup could beone such as demonstrated in FIGS. 17A and 17B. A sliding setup could beone such as demonstrated in FIG. 18. A narrow FOV setup could be onesuch as demonstrated in FIG. 16C.

In step 200, the system compares the determined detector element setupfrom the steps of dotted box 185 with subject scan information. Thisinformation is based on the subject of the scan (i.e. heart, thyroid,brain, breast, etc.) as well as the type of scan being performed.

In the steps of dotted box 198, an imaging operation is performed basedon the installation information compared with the subject scaninformation. If there is a good fit between the installationinformation, the corresponding scan to the detector element is selected.This is indicated by the horizontal lines. Step 202 to scan with eachdetector column across sixty degrees of the total range (such as inFIGS. 20A-20C) is generally performed when the staggered setup isdetermined in step 188 and that matches well with the subject scaninformation. Step 204 to scan including sliding edge detector elementsis generally performed when the sliding setup is determined in step 190and that matches well with the subject scan information. Step 206 toscan focusing with edge of a detector head with installed elements isgenerally performed when the narrow FOV setup is determined in step 192and that matches well with the subject scan information. Step 208 toscan using a custom scan scenario is generally performed when theinstallation setups do not match with the subject scan information orare not in any predefined arrangement.

FIGS. 20A-20C show the details of an imaging operation of step 202 whereeach detector column scans across sixty degrees across the total range.This could be best executed for a system of FIGS. 17A and 17B asdiscussed in detail above. Odd detector columns have odd detectorelements installed and even detector columns have even detector elementsinstalled. Therefore, to get a full scan of the subject, the systemwould have to orbitally rotate each detector column sixty degrees duringthe total imaging operation.

FIG. 20A shows a system with fully populated detector columns 22 with agantry orbital rotation range 210 of sixty degrees. The detector armscan be extended radially in the system. While the detector columns arefully populated, the detector elements in each detector column are not,as discussed above.

FIG. 20B shows a staggered imaging operation during the first threemovement locations, covering a gantry orbital rotation range 212 ofthirty degrees.

FIG. 20C shows a staggered imaging operation during the final threemovement locations, covering an additional gantry orbital rotation range214 of thirty degrees. Thus, each angle of a scanning operation iscovered by an even and an odd detector element. The imaging operationmay take longer than a system with fully populated detector elements,but the system can be cheaper due to having only half of the totaldetector elements in the system.

As contemplated, the various embodiments provide a lower cost,upgradable, and customizable system for imaging operations. Allfunctionality can be preserved, yet with a tradeoff of cost vs.acquisition time.

The configurable and controllable system of some embodiments could becontrolled by user input. Thus, the user can override the automaticoperation of the system and take full specific control of components ofthe system through a user interface.

Various embodiments provide configurations for arm assemblies that maybe used with an NM camera having pivoting heads. In some embodiments, atelescopic in/out motion for columns holding heads may be provided. Thetelescopic in/out motion in various embodiments allows for a smalleroutside diameter of a gantry while allowing a desired range of motion.Further, counterbalancing of the telescopic in/out motion for thecolumns may be provided. Counterbalancing may allow for the use ofweaker motors to articulate detector heads, and also provide improvedsafety (for example, in the case of motor failure or power outage).

Various embodiments may utilize detector arms that are arranged intelescopic configurations to provide for a desired range of radialmotion in a compact package. FIG. 21A provides a perspective schematicview of a detector arm assembly 1000 in an extended position, and FIG.21B provides a perspective schematic view of the detector arm assembly1000 in a retracted position. As seen in FIGS. 21A and 21B, the detectorarm assembly 1000 includes a stator 1010, a detector head 1020, a radialmotion motor 1030, and a detector head belt 1040.

The stator 1010 is configured to be fixedly coupled to a gantry having abore. As used herein, “fixedly coupled” may be understood to mean thatthe stator 1010 does not move with respect to the gantry when mounted inits intended fashion and an imaging system using the detector armassembly 1000 is used in its intended fashion. One stator 1010 and onedetector arm assembly 1000 are shown in FIGS. 21A and 21B; however, itmay be noted that plural stators 1010 may be mounted about the bore of agantry for which plural corresponding detector heads 1020 may beutilized to image an object within the bore.

The detector head 1020 includes a carrier section 1022 that is slidablycoupled to the stator 1010 and configured to be movable along a radialdirection 1001 in the bore relative to the stator 1010. Thus, thedetector head 1020 may be articulated radially inwardly (toward thecenter of the bore) or radially outwardly (away from the center of thebore) to place the detector head 1020 in a desired position for imaging.It may be noted that the carrier section 1022 and the stator 1010 may bedirectly or indirectly slidably coupled to each other. For example, insome embodiments, the carrier section 1022 and stator 1010 may bedirectly slidably coupled to each other, for instance, with one of thecarrier section 1022 or stator 1010 including a guide that slidablyaccepts a rail of the other. In other embodiments, for increasedcompactness in the retracted position, the detector arm assembly 1000may be configured as a telescoping assembly with an intermediate member(e.g., slider block 1050) interposed between the stator 1010 and carriersection 1022, with the intermediate member slidably coupled to thestator 1010 and carrier section 1022 separately, providing an example ofan indirect slidable coupling between the stator 1010 and carriersection 1022. As seen in FIG. 21A, the detector head 1020 may beunderstood as being distally positioned (e.g., positioned more radiallyinwardly than the stator 1010). One or more detectors (e.g., one or moreCZT detectors), which may be pivoted or tilted within the detector head1020, may be positioned in a distal portion of the detector head 1020.It may be noted that the detector head 1020 may include one or moreshielding members (e.g., for shielding electronics of a detector modulefrom radiation), and may be configured to provide cooling (e.g., bypassing a flow of air over cooling fins) to dissipate heat generated byelectronics associated with the detectors.

In various embodiments, the radial motion motor 1030 is operably coupledto at least one of the detector head 1020 or the stator 1010. In theembodiment depicted in FIGS. 21A and 21B, the radial motion motor 1030is mounted to the carrier section 1022 of the detector head 1020.Generally, the radial motion motor 1030 is used to drive the detectorhead belt 1040 to articulate the detector head 1020 radially (e.g.,inwardly toward the center of the bore or outwardly away from the centerof the bore). For example, a drive shaft of the radial motion motor 1030may be rotated to drive the detector head belt 1040. The radial motionmotor 1030 may also be used to help secure or maintain the detector headbelt 1040 in a desired position (e.g., by being prevented or inhibitedfrom rotating). It may be noted that, while a motor and belt are used inthe depicted embodiment (e.g., radial motion motor 1030 is utilized todrive the detector head belt 1040 and to articulate the detector head1020 radially), other devices, systems, or mechanisms may be utilized toarticulate the detector head 1020 radially in other embodiments.

The depicted detector head belt 1040 is operably coupled to the radialmotion motor 1030 and to the carrier section 1022 of the detector head1020, with rotation of the radial motion motor 1030 (e.g., rotation of adrive or output shaft of the radial motion motor) causing movement ofthe detector head 1020 along the radial direction 1001. In theillustrated embodiment, the detector head belt 1040 passes around adrive shaft and/or gear of the radial motion motor 1030 and around adetector head gear 1042 mounted to the carrier section 1022. Thedepicted detector head gear 1042 is mounted to an opposite end of thecarrier section 1022 than the radial motion motor, with the detectorhead belt 1040 extending along most or all of the length of the carriersection 1022 in the radial direction 1001.

As mentioned above, for increased compactness in the retracted position,the detector arm assembly 1000 may be configured as a telescopingassembly with an intermediate member (e.g., slider block 1050)interposed between the stator 1010 and carrier section 1022, with theintermediate member slidably coupled to the stator 1010 and carriersection 1022 separately, providing an example of an indirect slidablecoupling between the stator 1010 and carrier section 1022. As seen inFIG. 21A, the detector arm assembly 1000 includes a slider block 1050interposed between the detector head 1020 (e.g., the carrier section1022 of the detector head 1020) and the stator 1010. The slider block1050 is slidably coupled to the stator 1010 and configured to bemoveable in the radial direction 1001 with respect to the stator 1010.For example, one of the slider block 1050 and stator 1010 may include aguide that accepts a rail of the other. Also, the carrier section 1022of the detector head 1020 is slidably coupled to the slider block 1050and configured moveable in the radial direction 1001 with respect to theslider block 1050. For example, one of the slider block 1050 and carriersection 1022 may include a guide that accepts a rail of the other.

In various embodiments, one or more belts may be fixed or coupled to theone or more of the stator 1010, slider block 1050, or carrier section1022 to articulate the detector head 1020 in the radial direction 1001,or to articulate the detector arm assembly 1000 between extended andretracted positions. FIG. 22 provides a side perspective view of thedetector arm assembly 1000, and FIG. 23 provides an opposite sideperspective view of the detector arm assembly 1000.

As best seen in FIGS. 22 and 23, the slider block 1050 is fixed to thedetector head belt 1040 at point 1051. Accordingly, the slider block1050 moves in the radial direction 1001 with a portion 1041 of thedetector belt. It may be noted that portion 1043 of the detector belt1040, disposed on that opposite side of detector head gear 1042 from theportion 1041, moves oppositely in or along the radial direction 1001 asthe slider block 1050. The point 1051 where the slider block 1050 isfixed to the detector head belt 1040 may be the location of mounting toa bracket or clip 1052 used to fix the slider block 1050 to the detectorhead belt 1040.

As also seen in FIGS. 22 and 23, the detector arm assembly 1000 alsoincludes an idler belt 1060. The depicted idler belt 1060 is mounted toidler gears 1062, 1064 disposed on the slider block 1050. In theillustrated embodiment, the idler gears 1062, 1064 are mounted onopposite ends 1063, 1065, respectively, of the slider block 1050. Theidler belt 1060 is fixed to the carrier section 1022 at point 1067(e.g., via a clip or bracket as discussed in connection with point 1051)and to the stator 1010 at point 1068 (e.g., via a clip or bracket asdiscussed in connection with point 1051). The slider block 1050 moves inthe radial direction 1001 with a portion 1073 of the idler belt 1060relative to the stator 1010. Also, the carrier section 1022 moves in theradial direction 1001 with a portion 1071 of the idler belt 1060relative to the slider block 1050. With the portion 1073 and the portion1071 on opposite sides of the idler gears 1062, 1064 as shown in FIG.23, the stator 1010 and the carrier section 1022 move oppositely to eachother along the radial direction 1001 with respect to the slider block1050. Use of the idler belt 1060 thus results in about twice the totalmovement of the detector head 1020 with respect to the stator 1010 forthe same motor rotation and/or similar retracted length compared toexamples that do not use the idler belt 1060 and slider block 1050 (seealso, e.g., FIG. 3 and related discussion). It may be noted thatelectrical cables 1080 may be disposed about the idler belt 1060, withthe electrical cables 1080 extending along with the detector head 1020to provide electrical communication with the detector head 1020 in thevarious positions at which the detector head 1020 may be disposed.

In various embodiments, all or a portion of the stator 1010, detectorhead 1020, and/or slider block 1050 may be protected or contained withina cover. The cover may telescope with the detector arm assembly 1000 toprovide coverage over a range of motion while still providingcompactness in a retracted position. FIG. 24A provides a perspectiveview of a cover system 1100 in an extended position, and FIG. 24Bprovides a perspective view of the cover system 1100 in a retractedposition. The illustrated cover system 1100 includes a distal cover 1110and an outer cover 1120. As seen in FIGS. 24A and 24B, the distal cover1110 is mounted to and moves with the detector head 1020. The distalcover 1110 nests inside the outer cover 1120 in the retracted position(see FIG. 24B) and extends from the outer cover 1120 in the extendedposition (see FIG. 24A).

As indicated herein, in various embodiments a plurality of detector armassemblies (e.g., detector arm assemblies 1000) may be distributed abouta bore of a gantry. FIG. 25 provides a perspective view of an imagingsystem 1200. The imaging system includes a gantry 1210 and detector armassemblies 1220. It may be noted that the detector arm assemblies may begenerally similar to the detector arm assembly 1000 discussed herein.

As seen in FIG. 25, the gantry 1210 is a radial gantry and includes abore 1222 about which the detector arm assemblies 1220 are distributed.As also seen in FIG. 25, some of the detector arm assemblies 1220 are inan extended position, and some are in a retracted position. It may benoted that, in various embodiments, counterweights may be employed, forexample, to improve safety and/or to reduce an amount of power or energyrequired to articulate detector arm assemblies. In various embodiments,a counterweight may be coupled to at least one of the slider block orthe detector head, with the counterweight configured to move oppositelyin a radial direction to the detector head. For example, if the detectorhead moves radially inward, the counterweight may move radially outward.As another example, if the detector head moves radially outward, thecounterweight may move radially inward.

FIG. 26A provides a schematic view of a detector arm assembly 1300 in aretracted position, and FIG. 26B provides a schematic view of thedetector arm assembly 1300 in an extended position. The detector armassembly 1300 may be generally similar in certain respects to thedetector arm assembly 1000 disclosed herein. The depicted detector armassembly 1300 includes a stator 1310, a detector head 1320, a sliderblock 1330, and an idler belt 1340. The detector arm assembly 1300 alsoincludes a counterweight 1350, a counterweight pulley 1360, a statorpulley 1370, and a cable 1380. The counterweight 1350 may be slidablycoupled to the stator 1310 via rail 1351. The counterweight pulley 1360is mounted to the counterweight 1350, and the stator pulley 1370 ismounted to the stator 1310. As seen in FIGS. 26A and 26B, the cable 1380is wrapped partially about the stator pulley 1370 and the counterweightpulley 1360. As the detector head 1320 is articulated in direction 1381(from the retracted position to the extended position), the cable 1380is pulled around the counterweight pulley 1360 and the stator pulley1370, drawing the counterweight 1350 upward in direction 1382.

In some embodiments, reduced travel of a counterweight relative totravel of a detector head may be provided, for example, with one or moreadditional pulleys. FIG. 27A provides a schematic view of a detector armassembly 1400 in a retracted position, and FIG. 27B provides a schematicview of the detector arm assembly 1400 in an extended position. Thedetector arm assembly 1400 may be generally similar in certain respectsto the detector arm assembly 1000 disclosed herein. The depicteddetector arm assembly 1400 includes a stator 1410, a detector head 1420,a slider block 1430, and an idler belt 1440. The detector arm assembly1400 also includes a counterweight 1450, counterweight pulley 1460, afirst stator pulley 1470, a second stator pulley 1471, and a cable 1480.The counterweight 1450 may be slidably coupled to the stator 1410 viarail 1451. The counterweight pulley 1460 is mounted to the counterweight1450, and the first stator pulley 1470 and second stator pulley 1471 aremounted to the stator 1410. As seen in FIGS. 27A and 27B, the cable 1480is wrapped partially about the first stator pulley 1470, the secondstator pulley 1471, and the counterweight pulley 1460. As the detectorhead 1420 is articulated in direction 1481 (from the retracted positionto the extended position), the cable 1480 is pulled around thecounterweight pulley 1460, and the first stator pulley 1470 and secondstator pulley 1471, drawing the counterweight 1450 upward in direction1482.

It may be noted that, in various embodiments, other arrangements may beemployed additionally or alternatively to the use of pulleys andcounterweights. In some embodiments, counter-balancing may be providedthat may be utilized in a number of different orientations, instead ofjust up-and-down with respect to a gravitational field. For example,FIG. 28A provides a schematic view of a detector arm assembly 1500 in aretracted position, and FIG. 28B provides a schematic view of thedetector arm assembly 1500 in an extended position. The detector armassembly 1500 may be generally similar in certain respects to thedetector arm assembly 1000 disclosed herein. The depicted detector armassembly 1500 includes a stator 1510, a detector head 1520, a sliderblock 1530, and an idler belt 1540. The detector arm assembly 1500 alsoincludes a counterweight 1550, a first stator pulley 1570, a secondstator pulley 1571, and a cable 1580. The counterweight 1550 may beslidably coupled to the stator 1510 via rail 1551. The first statorpulley 1570 and second stator pulley 1571 are mounted to opposite ends(in the radial direction) of the stator 1510, with the cable 1580forming a loop 1590 around the stator 1510. The cable 1580 is attachedto the counterweight 1550 at point 1591 and to the slider block 1530 atpoint 1592. As the detector head 1520 is articulated in direction 1581(from the retracted position to the extended position), the downwardmotion of the slider block 1530 causes a clockwise rotation of the cable1580 about the stator 1510, drawing the counterweight 1550 upward indirection 1582. It may be noted that, via the use of the cable 1580forming the loop 1590, the detector arm assembly may be oriented indifferent directions and still provide effective counterbalancing,including oriented such that the detector head moves toward the extendedposition in opposition to a gravitational field. It may further be notedthat, in the illustrated embodiment, the detector arm assembly 1500includes a radial motion motor 1502 mounted to the stator 1510, with theradial motion motor directly driving the cable 1580 at the first statorpulley 1570 to articulate the detector head 1520 and counterweight 1550oppositely along a radial direction. It may be noted that generallysimilar loops may be implemented in additional embodiments, for exampleembodiments that incorporate various aspects of the previouslyillustrated examples.

Still other arrangements may be employed for counterbalancing in variousembodiments. For example, a spring loaded spool may be employed invarious embodiments. FIG. 29A provides a schematic view of a detectorarm assembly 1600 in a retracted position, and FIG. 29B provides aschematic view of the detector arm assembly 1600 in an extendedposition. The detector arm assembly 1600 may be generally similar incertain respects to the detector arm assembly 1000 disclosed herein. Thedepicted detector arm assembly 1600 includes a stator 1610, a detectorhead 1620, a slider block 1630, and an idler belt 1640. The detector armassembly 1600 also includes a spring-loaded spool 1650 and a cable 1680.The spring-loaded spool 1650 includes a spring that resists thewithdrawal of the cable 1680 from the spring-loaded spool 1650. The freeend of the cable 1680 (the end outside of the spring-loaded spool 1650)is attached to the detector head 1620. As the detector head 1620 isarticulated in direction 1681 (from the retracted position to theextended position), the spring-loaded spool 1650 provides a force actingupward in direction 1682 as seen in FIGS. 29A and 29B. It may be notedthat the detector arm assembly may be oriented in different directionsand still provide effective counterbalancing, including oriented suchthat the detector head moves toward the extended position in oppositionto a gravitational field. The spring force for the spring-loaded spool1650 may be selected relative to the detector weight, and may beadjustable or variable depending on the orientation of the detector headwith respect to gravity.

As also indicated elsewhere herein, in various embodiments a pluralityof detector arm assemblies (e.g., detector arm assemblies 1000) may bedistributed about a bore of a gantry. It may be noted that, in variousembodiments, each of the detector arm assemblies of an imaging systemmay be provided with counterweights. Alternatively, some detector armassemblies may be provided with counterweights or counterbalancing whileother detector arm assemblies are not provided with counterweights orcounterbalancing. For example, counterbalancing may be provided forgantry locations for which counterbalancing is particularly desirable oradvantageous, while counterbalancing is not provided for other locationsto reduce expense and/or space requirements.

FIG. 30 provides a schematic depiction of various gantry locations. InFIG. 30 an oval gantry 3000 is depicted; however, other shapes such ascircular may be employed in various embodiments. Detector arm assemblies3010, schematically depicted as arrows may be distributed about a bore3002 of the gantry 3000 and oriented toward the center of the gantry.The detector arm assemblies may be categorized in three groups—lateralarms 3020, upper vertical arms 3030, and lower vertical arms 3040. Thelateral arms 3020 may include all arms oriented within 30 degrees ofhorizontal (with a horizontal direction defined as being normal to agravitational field), with the remaining arms being grouped as eitherupper or lower vertical arms.

With the lateral arms 3020 acting generally normal to a gravitationalfield, there may be fewer safety concerns regarding an arm striking apatient while accelerated by gravity. Also, with the lateral armsextending and retracting normal to a gravitational field, relativelysmaller power amounts may be required to articulate the arms.Accordingly, the lateral arms 3020 may be provided withoutcounterweights or counterbalancing.

The upper vertical arms 3030, however, are retracted generally against agravitational force, and thus it may be desirable for powerconsiderations to provide the upper vertical arms 3030 withcounterbalancing to reduce the power requirements for retracting thedetectors. Further still, because the upper vertical arms 3030 aredisposed above the patient (with respect to gravity), it may further bedesirable to provide counterbalancing for safety purposes.

The lower vertical arms 3040 are disposed below the patient (withrespect to gravity), and thus safety may not be an issue with respect todesirability of counterbalancing the lower vertical arms. The lowervertical arms 3040, however, are extended generally against agravitational force, and thus it may be desirable for powerconsiderations to provide the upper vertical arms with counterbalancingto reduce the power requirements for extending the detectors.Accordingly, in some embodiments, only the upper vertical arms 3030 maybe provided with counterbalancing, while the lower vertical arms 3040and lateral arms 3020 may not be provided with counterbalancing. Inother embodiments, the upper vertical arms 3030 and lower vertical arms3040 may be provided with counterbalancing, while the lateral arms 3020are not provided with counterbalancing.

The various embodiments and/or components, for example, the modules, orcomponents and controllers therein, also may be implemented as part ofone or more computers or processors. The computer or processor mayinclude a computing device, an input device, a display unit and aninterface, for example, for accessing the Internet. The computer orprocessor may include a microprocessor. The microprocessor may beconnected to a communication bus. The computer or processor may alsoinclude a memory. The memory may include Random Access Memory (RAM) andRead Only Memory (ROM). The computer or processor further may include astorage device, which may be a hard disk drive or a removable storagedrive such as a flash memory disk drive, optical disk drive, and thelike. The storage device may also be other similar means for loadingcomputer programs or other instructions into the computer or processor.

As used herein, the term “computer” or “module” may include anyprocessor-based or microprocessor-based system including systems usingmicrocontrollers, reduced instruction set computers (RISC), applicationspecific integrated circuits (ASICs), logic circuits, and any othercircuit or processor capable of executing the functions describedherein. The above examples are exemplary only, and are thus not intendedto limit in any way the definition and/or meaning of the term“computer”.

The computer or processor executes a set of instructions that are storedin one or more storage elements, in order to process input data. Thestorage elements may also store data or other information as desired orneeded. The storage element may be in the form of an information sourceor a physical memory element within a processing machine.

The set of instructions may include various commands that instruct thecomputer or processor as a processing machine to perform specificoperations such as the methods and processes of the various embodimentsof the invention. The set of instructions may be in the form of asoftware program. The software may be in various forms such as systemsoftware or application software. Further, the software may be in theform of a collection of separate programs or modules, a program modulewithin a larger program or a portion of a program module. The softwarealso may include modular programming in the form of object-orientedprogramming. The processing of input data by the processing machine maybe in response to operator commands, or in response to results ofprevious processing, or in response to a request made by anotherprocessing machine.

As used herein, the terms “software” and “firmware” may include anycomputer program stored in memory for execution by a computer, includingRAM memory, ROM memory, EPROM memory, EEPROM memory, and non-volatileRAM (NVRAM) memory. The above memory types are exemplary only, and arethus not limiting as to the types of memory usable for storage of acomputer program.

As used herein, a structure, limitation, or element that is “configuredto” perform a task or operation is particularly structurally formed,constructed, or adapted in a manner corresponding to the task oroperation. For purposes of clarity and the avoidance of doubt, an objectthat is merely capable of being modified to perform the task oroperation is not “configured to” perform the task or operation as usedherein. Instead, the use of “configured to” as used herein denotesstructural adaptations or characteristics, and denotes structuralrequirements of any structure, limitation, or element that is describedas being “configured to” perform the task or operation.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the variousembodiments of the invention without departing from their scope. Whilethe dimensions and types of materials described herein are intended todefine the parameters of the various embodiments of the invention, theembodiments are by no means limiting and are exemplary embodiments. Manyother embodiments will be apparent to those of skill in the art uponreviewing the above description. The scope of the various embodiments ofthe invention should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

In the appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein.” Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects. Further, thelimitations of the following claims are not written inmeans-plus-function format and are not intended to be interpreted basedon 35 U.S.C. §112, sixth paragraph, unless and until such claimlimitations expressly use the phrase “means for” followed by a statementof function void of further structure.

This written description uses examples to disclose the variousembodiments of the invention, including the best mode, and also toenable any person skilled in the art to practice the various embodimentsof the invention, including making and using any devices or systems andperforming any incorporated methods. The patentable scope of the variousembodiments of the invention is defined by the claims, and may includeother examples that occur to those skilled in the art. Such otherexamples are intended to be within the scope of the claims if theexamples have structural elements that do not differ from the literallanguage of the claims, or if the examples include equivalent structuralelements with insubstantial differences from the literal languages ofthe claims.

What is claimed is:
 1. A detector arm assembly comprising: a statorconfigured to be fixedly coupled to a gantry having a bore defining aradial direction; a detector head including a carrier section, thecarrier section slidably coupled to the stator and configured to bemovable in the radial direction in the bore relative to the stator; aradial motion motor operably coupled to at least one of the detectorhead or the stator; and a detector head belt extending along the radialdirection and operably coupled to the radial motion motor and thecarrier section, wherein rotation of the radial motion motor causesmovement of the detector head belt and the detector head along theradial direction.
 2. The detector arm assembly of claim 1, furthercomprising a slider block interposed between the detector head and thestator, the slider block slidably coupled to the stator and configuredto be moveable in the radial direction with respect to the stator, thecarrier section of the detector head slidably coupled to the sliderblock and configured to be moveable in the radial direction with respectto the slider block.
 3. The detector arm assembly of claim 2, whereinthe slider block is fixed to the detector head belt at at least onepoint, wherein the slider block moves in the radial direction with aportion of the detector head belt.
 4. The detector arm assembly of claim3, further comprising an idler belt mounted to idler gears disposed onthe slider block, the idler belt fixed to the carrier section at atleast one point and to the stator at at least one point, wherein theslider block moves in the radial direction with a portion of the idlerbelt relative to the stator.
 5. The detector arm assembly of claim 4,wherein the idler belt gears include a first idler belt gear disposed ata first end of the slider block and a second idler belt gear disposed ata second, opposed end of the slider block.
 6. The detector arm assemblyof claim 2, wherein the radial motion motor is mounted to the carriersection.
 7. The detector arm assembly of claim 1, further comprising acounterweight coupled to at least one of the slider block or thedetector head, the counterweight configured to move in an oppositeradial direction to the detector head.
 8. The detector arm assembly ofclaim 7, wherein the counterweight is coupled to a cable forming a looparound the stator.
 9. The detector arm assembly of claim 7, wherein thedetector head is coupled to a rotary spring coupled to the stator. 10.The detector arm assembly of claim 7, further comprising a counterweightpulley mounted to the counterweight, a stator pulley mounted to thestator, and a cable wrapped at least partially about the stator pulleyand the counterweight pulley.
 11. A detector arm assembly comprising: astator configured to be fixedly coupled to a gantry having a boredefining a radial direction; a detector head including a carriersection, the carrier section slidably coupled to the stator andconfigured to be movable in the radial direction in the bore relative tothe stator; a slider block interposed between the detector head and thestator, the slider block slidably coupled to the stator and configuredto be moveable in the radial direction with respect to the stator, thecarrier section of the detector head slidably coupled to the sliderblock and configured to be moveable in the radial direction with respectto the slider block; and a detector head belt extending along the radialdirection operably coupled to the carrier section, the detector headbelt configured to move along the radial direction, wherein movement ofthe detector head belt causes movement of the detector head in theradial direction.
 12. The detector arm assembly of claim 11, wherein theslider block is fixed to the detector head belt at at least one point,wherein the slider block moves in the radial direction with a portion ofthe detector head belt.
 13. The detector arm assembly of claim 12,further comprising an idler belt mounted to idler gears disposed on theslider block, the idler belt fixed to the carrier section at at leastone point and to the stator at at least one point, wherein the sliderblock moves in the radial direction with a portion of the idler beltrelative to the stator.
 14. The detector arm assembly of claim 13,wherein the idler belt gears include a first idler belt gear disposed ata first end of the slider block and a second idler belt gear disposed ata second, opposed end of the slider block.
 15. The detector arm assemblyof claim 11, further comprising a radial motion motor mounted to thecarrier section and operably coupled to the detector head belt.
 16. Thedetector arm assembly of claim 11, further comprising a counterweightcoupled to at least one of the slider block or the detector head, thecounterweight configured to move in an opposite radial direction to thedetector head.
 17. An imaging system comprising: a gantry defining abore, the bore defining a radial direction; and plural detector armassemblies distributed about the bore, wherein at least some of thedetector arm assemblies comprise: a stator configured to be fixedlycoupled to the gantry; a detector head including a carrier section, thecarrier section slidably coupled to the stator and configured to bemovable in the radial direction in the bore relative to the stator; aradial motion motor operably coupled to at least one of the detectorhead or the stator; a detector head belt extending along the radialdirection and operably coupled to the radial motion motor and thecarrier section, wherein rotation of the radial motion motor causesmovement of the detector head belt and the detector head along theradial direction; and a slider block interposed between the detectorhead and the stator, the slider block slidably coupled to the stator andconfigured to be moveable in the radial direction with respect to thestator, the carrier section of the detector head slidably coupled to theslider block and configured to be moveable in the radial direction withrespect to the slider block.
 18. The imaging system of claim 17, whereinat least some of the detector arm assemblies include a counterweightcoupled to at least one of the slider block or the detector head, thecounterweight configured to move in an opposite radial direction to thedetector head.
 19. The imaging system of claim 18, wherein at least oneof the detector arm assemblies includes the counterweight and at leastone of the detector arm assemblies does not include the counterweight.20. The imaging system of claim 18, wherein the plural detector headsinclude a lateral group and a vertical group, wherein the detector headsof the lateral group do not include the counterweight.